Andrew Tubbiolo writes:

I removed the table, and it looks like the ways on the knee
are worn where most of the work was done. There is also a deep
gouge where it looks like a chip worked it way in and got dragged
back and forth. What kind of shop should I look for to remachine
my ways, and any idea how much it will cost me?

Sounds exactly like my Bridgeport. This is the typical wear pattern,
progressively more toward the middle, with a slant down to the outside.
I had some scoring ("gouge") like you mention, and in one case I
actually found the cause to be a speck of carbide or diamond embedded in
the mating cast iron surface, ouch!

I improvised some effective methods of doing the machining of the
horizontal knee ways, get this, on the machine itself!

I "self-machined" the horizontal knee ways with a dovetail bit, rotating
the turret and sliding the ram in small increments along the surface.
Each increment required lowering the knee,
unlocking/rotating/extending/locking the ram, and applying power while
raising the knee. The dovetail bit I made by brazing carbide inserts
onto a frustrum of mild steel, such that they would scrape flat 2.25" OD
/ 1.25" ID donuts. (A regular dovetail bit doesn't do this, since it
has a slight taper up towards its center, like an endmill.)

Properly overlapped, this yields a surface flat and automatically true
to the ram's datum alignment, with a "noise" variance of only about
0.001" to be tidied up by scraping.

The turret swing and ram extension doesn't quite reach the ends of the
knee ways, so there are a few inches at each end to be scraped down more
or less by hand. After scraping off the entire 0.015" by hand on one of
these 4 areas, which was exhausting, I made another tool, a "precision
plow", which consisted of a 1x6 in cast-iron shoe with a scraped-flat
bottom, with a length of 1/2" round bar attached, and a carbide
threading insert on the end of the bar. This I could adjust on a
surface plate to have the tip of the threading insert precisely 0.003"
or so above the horizontal plane of the "sole" of the shoe. Then by
skating the shoe on the already self-milled areas by hand, I could plow
a network of grooves into the unreachable unmilled areas. Once so
grooved, I used a die grinder to quickly remove the bulk of the material
(about 0.012 of the 0.015 thickness), using the grooves to monitor and
control the depth of hand grinding. The final 0.003 or so I hand
scraped.

The grooving is critical. A die grinder removes a lot of material fast,
but it is uncontrolled and inherently imprecise, and therefore useless
on its own. The grooves are a kind of "topo map" to measure how far
down you have ground. I chose the 0.003" as a remnant because it seemed
like the worst-case error I might make between the plow and the grinder.

Making the dovetail bit and the plow took longer than applying them.

I'm not sure exactly how a knee is machined in the more conventional
manner. It would take a very big dovetail bit on a very big machine to
handle the size of the knee.

In theory one can scrape it all off by hand to return to alignment, but
I learned that hogging off material with a scraper is days of hard work.
Much better to machine off the bulk and finish with hand scraping.